Milestone 1 of dynamic-by-default, the runtime half: NaN-boxed values in one
machine word, a mark-sweep heap, and the operations over them.
A double is itself, which is what a language with a physics loop and a float
calculator in its corpus wants; everything else hides in the quiet-NaN space,
three tag bits and a 48-bit payload that is exactly an x86-64 user pointer.
The negative-NaN collision is answered by canonicalising every NaN on the way
in, which flan_rt.c had already decided was the right thing to print. An i64
past the payload goes on the heap rather than becoming a 48-bit integer with a
64-bit name.
The collector is mark-sweep and nothing else -- no generation, no barrier, no
free list -- because the answer to wanting it faster is to type the program.
Roots are pushed, not scanned: NaN-boxing makes a conservative guess wrong in
both directions, and flan_dev.c's frame chain is the precedent. A fixed ring
of the last sixty-four allocations is marked unconditionally, which closes the
window where an expression with two constructors in it can collect its own
first result before the compiler has rooted either.
A type mismatch traps rather than aborting, through a flan_trap exported from
flan_rt.c so it takes the same path the six existing traps take: parked for
inspection in a dev session, dead where it stands otherwise. The sentence
names the operation, both tags as words, and both values.
flan_dyn.c is its own translation unit and nothing in the release runtime
names a symbol in it, so a program with no dyn operation links no collector
and --no-gc can be file-level selection rather than an argument with the
linker.
docs/SPIKE-DYNAMIC.md carries the argument. test/dyn_ops.c drives every
operation and all twenty-four refusals from C, the way dev_limits.c does,
including a million allocations against a hundred live and the control that
says an unrooted object really is reclaimed.
The !-means-mutates convention distinguished nothing — there is no
immutable counterpart to contrast with — so every mutating name drops
the mark: sort, sort-by, sort-bytes, swap, reverse, append, append-i64,
append-f64, encode-rune, split-next, map-remove, map-next, and the test
helpers beside them. Two could not simply shed it: map! is map-in-place,
because map is the into transform's word and means the non-mutating
thing; put! is put-at, because put is the Map builtin. The ?-means-asks
convention stays. Dated records keep the old spellings; watch.clj's
reset-spies! and the other Clojure names are not ours to rename.
The backend had a full dev story for everything except the one thing the
break loop reads: emit.ml pushes a shadow-stack frame on entry to every body
in a dev build and x86.ml pushed none, so an --x86 session answered backtrace,
locals, inspect and globals with "this program was not built with --dev",
which was false of it.
emit_fn now builds the same four words runtime/flan_dev.c describes -- the
previous head, a static descriptor, and a table of one address per slot, null
until the binding that fills it has run. The push is emitted at the head of
the body buffer rather than into the prologue's, because the prologue is where
the incoming registers still hold the arguments and every instruction of it
clobbers rax. The pop is one store at the epilogue label: this backend has one
epilogue and a return, the body's tail and the transfer exit all arrive there,
where emit.ml needs the same restore at five separate rets.
Two decisions are taken from emit.ml rather than reasoned out again, so that
the two dev builds answer a stopped frame identically. A function with no
named slot gets no table and reports no slots -- there the gate buys mem2reg
an alloca that does not escape, here it buys nothing but agreement, and
agreement is the only thing the break loop can check. And the descriptor's
bytes do not go through string_const: that counter is what decides whether an
expression thunk's module may be unloaded, and counting a descriptor in it
would pin every C-x C-e module's mapping for ever.
The descriptors are the one constant this backend emits that holds an address,
so they go in .data.rel.ro and not .rodata -- a relocation the loader applies
needs a section it may write, and a redefinition module is such an object.
Verified on an assembled module: R_X86_64_RELATIVE for the two pointers,
flan_frame_head through the GOT, no TEXTREL.
layout_ctx fills its globals table, which it never had to before. Reach's
ref_fingerprint asks whether a name is a global, and with an empty table no
name is one -- every frame would carry the hash of the empty set, the daemon
would recompute the real one, and the globals section would refuse a body
nobody had touched while its locals still read.
Release builds gain nothing: all of it is behind md.dev, and three corpus
programs emit byte-identical assembly before and after.
The new coverage stands up an --x86 daemon on dev-locals.flan and asks the
four questions, against the values the LLVM block above asserts of that same
program -- the claim is that the answers are the same and not merely
plausible. The existing --x86 two-process daemon gains one more: a backtrace
through a redefined body, which reports the installed body's own file, since
that descriptor travels in the module and a frame pointing at the host's would
name the body it replaced.
Four corrections to the prose and one to the test, none to the design.
The provenance line said "the name is Rust's or_else, the behaviour is
Rust's unwrap_or", which conflates two functions that differ in both
eagerness and return type — Rust's or_else takes a closure and answers
another Option. Java's Optional.orElse is the exact match, and its lazy
sibling orElseGet is the one already declined a paragraph above.
The helper reaching or-else's None branch at an owning type asserted a
refusal nobody had run. Compiled, it is "nothing here says what None is
an Option of — annotate the function's return type or the binding", so
the comment quotes that and the helper is a return type and nothing
else: its other branch was never called, in a program whose header says
every line is a claim.
read-file's comment claimed both restarts arrive unchanged and the test
runs use-value. Narrowed to the mechanism (nothing here establishes a
handler) plus the half that is actually executed.
And edn-read.flan now says what becomes of its defn wrapper when the
computed-initialiser work lands, since that is the only thing keeping
the motivating line from being written as the defvar.
The x86 backend ran initialisers from .init_array and the LLVM one refused
them by name, so (defvar frame Allocator (arena-new 262144)) — which the
author kept writing — was a program on one backend and an error on the other.
A rule that holds on one backend and not the other is not a rule.
The checker lifts a computed initialiser into a function of its own and the
global's initialiser becomes the call. That is what gives it a frame, which is
the bug underneath the feature: a `let` or a `match` in an initialiser indexed
a slot array of length zero and took the x86 emitter down with an uncaught
Invalid_argument.
Both backends call the lifted initialisers from main, after flan_rt_init and
before a line of the program's own code — Odin's __$startup_runtime shape, not
a constructor, so the runtime is up and the order is the compiler's to choose.
x86 keeps .init_array for one thing only, and it is named: writing the
constant image this backend has no folder for, which is standing in for the
other backend's object image rather than for a program.
The computed globals are sorted by what they read, transitively through the
functions they call, so a global written above the one it reads works and a
ring is refused with every name in it. A reload still re-runs nothing: a new
global with a computed initialiser starts as ZII on both backends.
The refusal that lived in x86.ml is now the checker's and is narrower. Nothing
can escape an initialiser — the handler and restart stacks are empty and every
frame it pushes it also pops — so what is refused is a signal or an
invoke-restart with no handler-bind or restart-case around it, which is inert
by construction. A restart-case inside one is ordinary code, which is what
makes (defvar data (Vec u8) (slurp "level.edn")) an ordinary program.
Three refusals go with the premise they rested on: a container global with a
computed initialiser, a union member in a defvar, and a data type case in one.
A defconst is untouched and keeps all three.
One change here is not about any of that. sand.flan carried an unfinished
line — (defvar game-data (embed (with-allocator frame ))), which parses as a
declaration whose type is (embed ...) — so the checker refused the file and
`dune test` was red at the tip of dev-loop before a line of this landed,
verified by stashing this work and rebuilding. It is commented out rather than
guessed at: the arena above it is the half that works, and what the global
should read is the author's to decide.
Two things the motivating line wanted and could not have.
or-else and some? are the first prelude family over (Option $t), and the
first that declares no {:where} at all: they move the payload out or read
the tag, and neither is an operation a type variable has to be admitted
to. So they instantiate at every type, including the ones that own
storage — where the answer is a header onto one of the two buffers and
the branch not taken is still the caller's to free, which the comment
says because "or a default" reads like it consumes the default.
none? is declined as (not (some? o)), and an unwrap that signals on None
is declined for the reason file-size is an Option at all: absence is a
reply and not a fault, and whether an empty one is an error is the
caller's question.
edn/read-file is worth having for one fact the package already argued:
every string in a Value is a copy, so the source buffer is dead the
moment read returns and nothing outside the call can be holding it. It
slurps against the heap by name — the one allocator this package names,
because the buffer's life is inside the call and is not the caller's
tier to choose — defers the free for the transfer path, and passes
slurp's FileError straight through with both restarts armed. Folding a
missing file into None would collapse the very distinction the Option
exists for.
There is no json/read-file and json.flan now says why: a Token's text is
a slice into the caller's buffer, so the prerequisite is a json/read
answering a self-contained document, and there is no Value type there to
answer with.
The defvar initialiser in the motivating line is still refused as
computed, so edn-read.flan writes it as a defn and says so; everything
inside the with-allocator is verbatim.
flan dev takes the hand-written backend unasked now: it is what that
backend was written for, it halves the C-c C-c round trip, and nothing it
builds outlives the session. Every other command is LLVM by default and
unmoved, which is what keeps lib/x86.ml's calling convention licensed.
--debug picks LLVM on its own rather than landing on the refusal: a
redefinition module from this backend carries no line table, so the one
flag someone types to get a debugger must not choose the backend without
one. --x86 --debug together is still refused, and now says which to drop.
What the flip costs is more than the forms this backend refuses. It
pushes no shadow stack, so a session built by it stops on an error and
cannot say where -- and the agent answered that with "this program was
not built with --dev", which is false of an x86 dev host. Dev.ask
rewrites it; the IR view refuses by name instead of failing to find a
define in a .s file; and a refusal at the host build or at C-c C-c names
--llvm rather than stopping at "unsupported".
flan-daemon-args carries the flag from Emacs, spliced into the one
argument list the daemon buffer's first line is now printed from.
`arena-new` is a builtin, so it is in no program's symbol table and `defs`
never mentioned it — which made the editor answer "the running program
defines no arena-new" about a name that works. The fix is not a better
refusal: it is that the seventy-eight names the checker answers without
being told are now in the reply, under a kind of their own.
check.ml carries the table, beside the arms it describes, because a table
in another file drifts from them with nothing said. test_flan reads both
the arms and the table and fails on either having a name the other does
not, in both directions — there is no reflecting over a match, so it reads
the source.
Each entry is a signature in `signature_of_fn`'s shape and one line. The
arms that do not have one shape say what is true instead of pretending:
`?` for an argument that may be left out, `|` for the types an arm really
takes, and the checker's own predicate names for the type-directed ones.
The three user-allocator names carry a bare name and no bracket list,
because they are refused wherever they are written.
`defs` grows a fifth string for the prose, and builtins are appended last
so a completion table does not bury the names being worked on. A defn has
no docstring to put there and does not get one here: the Tast keeps none,
and that is a different piece of work.
The editor reads the kind, not a special case. `flan-doc--where` and the
xref backend both answer before their empty-location branch, because a
global's missing location and a builtin's absent one are different facts
and only one of them is about the daemon.
`-dev-` was in every Emacs symbol this client owns and meant nothing to anyone
typing one: the daemon is `flan dev` at a shell, but from inside Emacs there is
no other kind of connection to distinguish it from. `M-x flan-dev` is now
`M-x flan`, `flan-dev-quit` is `flan-quit`, the private prefix `flan-dev--` is
`flan--`, and every defcustom follows — ninety-odd symbols, with the two files
renamed to emacs/flan.el and emacs/test-flan.el so the file names say the same
thing as the symbols in them.
No aliases. Renaming a defcustom breaks a config that names it and there is no
way around that; the repo has no precedent for softening one, and an alias left
behind is what keeps a rename from finishing. MANUAL.md says the old names are
gone and how to fix a config, which is the whole of the migration path.
Three strings are not symbols and keep their spelling: `.flan-dev.sock`, which
bin/main.ml writes and which a renamed variable searching for a renamed file
would simply never find; and the two buffer names `*flan-dev*` and ` *flan-dev*`,
which name the `flan dev` subcommand's own output rather than anything in elisp.
`flan dev` with a space is the CLI and is untouched everywhere.
The entry point also stops asking a question it already has the answer to. From
a buffer visiting a .flan file it starts that file; from anywhere else it reads
one from the minibuffer as before; `C-u` reads one either way, which is how you
start a second program without leaving the first. The current buffer is still
the only source of the default — the bug where a previous project won over the
buffer you were in was fixed by removing `flan--file` from that position, and
nothing here puts it back.
Four checks on the `interactive' form, evaluated on its own rather than by
calling the command, because calling it would build and launch a program and
the question is only which file the form arrives at and whether it had to ask.
A fifth asserts that nothing answers to the old names. test/test_emacs.ml loads
the test file by path and test/test_session.ml names the client file in a
comment, so the rename reaches those two lines; nothing else outside emacs/ and
the docs moved. Verified by byte-compiling every file
clean and by `dune test` and `@page`.
Three gaps in the first pass. The park flushes after the poll, which is the
only thing that gets a printing expression's line out of a fully buffered pipe
before the next run — now pinned by its position in the transcript. The globals
section under a parked break answers with everything skipped, which is a
different reply from the timeout a job nobody polled would give, so it is asked
for rather than assumed. And the render thunk's five-second sentence no longer
asks a parked program whether it is calling agent/poll.
The park waited on one flag and could do one thing, so C-x C-e on (+ 1 1) was
refused for want of a frame boundary — an expression that needs nothing from
the program, in a process holding every global the run left.
It waits on two now. A re-run leaves the park; a wake drains the agent's ring
and waits again, with the state still PARKED, which is what makes running the
thunk there exactly as safe as running it at a frame boundary: while parked
there is no concurrency to be unsafe against. The break loop is the precedent
and CL's spawned worker is deliberately not copied.
A thunk that stops now stops on a parked thread, so the restart ops refuse on
whether a break is engaged rather than on the state, and a paused expression
against the park is resumable.
#{{:a 1} {:a 1} {:a 2}} answers 2 whether tables=? compares anything or
compares nothing, so it was proving the count and not the compare. The
pair beside it isolates both halves: one map twice must collapse to 1,
and two maps of one entry each with different keys must stay 2, which is
what a size-only compare would get wrong.
And read's comment stops implying a property it does not have: empty
input answers (Some Value.Nil), indistinguishable from the document that
is nil. Empty is not malformed and the reader is not the thing that gets
to decide it is.
vendor/json is vendor/edn's shape with one decision reversed. edn never
allocates, so its tokens are views into the source buffer and escaped
strings are refused for want of anywhere to put the unescaped copy. This
one has an allocator, so it unescapes, and to unescape it copies —
string-of is the only function in the package that allocates, and it
copies even when there was no escape to resolve, because a Value whose
lifetime depended on which bytes happened to be in it is not a contract
anyone can hold. Odin answered the same question the same way:
tokenizer.odin allocates nothing, parser.odin's unquote_string does the
copy, and it clones in the no-escape branch too.
What that buys is at the bottom of test/programs/json.flan, which is
programs/edn.flan and programs/arena-edn.flan in one file because for
JSON they are one claim. The source buffer is overwritten with `?` bytes
while the document is live and the strings read back afterwards are
still the strings. arena-edn's header has a section admitting it cannot
do that.
Strict JSON and not Odin's JSON5 default, and the difference is where
most of the refusals come from: comments, single quotes, +1, .5, 1.,
0x1f, 01, NaN, Infinity and unquoted keys each get a sentence naming the
dialect they belong to, rather than one shared unexpected-byte. A lone
surrogate is refused too, and that one is forced rather than chosen —
rune-size answers None for the whole D800-DFFF block, so encode-rune!
would write nothing and the character would vanish.
The tokenizer refused #{} because "it needs a hash set to even
represent" — which is a claim about a reader, and a tokenizer represents
nothing. #{ now pushes } on the same balance stack { does, there is one
new token kind and no new closer, and err-set is gone rather than kept
with a message it no longer earns. skip-value needed nothing: it is
written against the depth and not against the kinds.
The dynamic reader moves out of test/programs/arena-edn.flan and into
vendor/edn/read.flan as (edn/read bytes), answering an (Option Value)
against whichever allocator the caller bound. Two decisions are written
down where they are made:
* a set is a Value.Set holding a deduplicated (Vec Value), because
(Map Value bool) does not typecheck — keyable refuses a key holding
a Vec or a Map — and restricting elements to keyable Values would
refuse #{[0 0] [1 0]}, which is the file this was built for. Insert
is O(n) against a structural value=?, so building the tileset's 54
pairs is 1458 comparisons, once.
* a Value copies every string into the allocator where a Token stays
a view. A view handed back out of the function that owns the buffer
is a dangling pointer, and free-all would not even take it. Odin's
json parser clones for the same reason.
An imported defdata was a refusal in load.ml — "not implemented yet
(milestone 4)" — and it had to go first. It is the type's name plus the
Type. half of a constructor symbol, which arrives as a Var node when the
case has no fields and a Struct node when it has; a match pattern needed
nothing, because a case resolves against the scrutinee's type and was
never a top-level name. programs/pkg-data.flan is that on its own.
programs/edn-read.flan reads assets/edn/tileset.edn, which is the
editor's real output: :texture-path and a :selected-cells of 54 integer
pairs, with no type declared for any of it. It also overwrites the
source buffer in place after reading and prints the document back, which
is the copy contract asserted rather than described.
[close] was the only way out of the accept loop that anybody ever took, and
an editor that is killed rather than quit never sends it. Four of the eight
orphans found on the author's machine were that.
The signal is the socket, not a new op: Emacs opens one connection for the
whole session and drops it only on paths that send [close] first, so an
editor left open overnight is an editor still attached and the grace cannot
accumulate under it. Armed only once a client has been there, so a daemon
still waiting for its first one is untouched. Parked sessions get the short
clock and live ones six times it, because a parked program is invisible and
a running one is a window somebody may be looking at.
Under --two-process the compiled program is a child of the daemon, and the
daemon is the only thing that ever ends it: the program is a loop with no
reason of its own to stop, and lib/dev.ml kills it from a Fun.protect finally
block on the way out. That block does not run when the daemon is SIGKILLed —
by a harness tearing down a daemon it gave up on, by a watchdog, by anybody —
and what was left behind was a program with ppid 1, sleeping, holding a socket
nothing will ever connect to. Eight of those were on the machine this was
written on, the oldest six days old, and one had been minted by this suite.
The child now arms PR_SET_PDEATHSIG when it starts its agent, gated on a
FLAN_DEV_PARENT the daemon sets and nothing else does, and closes the race
where the daemon died before the arming by comparing getppid against that pid
rather than against 1 — under a subreaper an orphan is not reparented to init.
The signal is SIGPWR and not SIGTERM, because the daemon's ordinary teardown
already sends the child SIGTERM and the child's stderr is the daemon's own; a
handler there would print "the daemon is gone" into the daemon's output on
every clean close. The handler writes one sentence, unlinks the agent socket
it bound, and exits 0, and it does nothing else because it can run on the game
thread inside stdio's lock.
A merged build arms none of this and must not. There the daemon is the
process, so a dead daemon is a dead program; its parent is whoever typed
flan dev, which is a shell or an emacs and not the session's owner. Merged
daemons do leak on this machine — four of the eight — but for a different
reason, which is that accept_loop has no idea whether its editor still exists.
That wants a mechanism that tracks the client rather than the parent, and it
is not this change.
The daemon's read end of the program's stdout pipe is also cloexec now. The
child used to inherit it, which is both a leak and the reason waiting for EOF
on that pipe could never have been the mechanism: the pipe always had a
reader. A printing program now takes SIGPIPE once its daemon is gone, which is
a second net under chatty programs and not a substitute — the test uses
dev-watch, which is silent, so that only the thing under test can end it.
The test spawns the two-process shape, sends one request so that what it kills
is demonstrably serving, reads the program's pid out of the daemon's
/proc children before killing it — it is a grandchild, so waitpid is ECHILD —
and SIGKILLs the daemon. SIGKILL and not SIGTERM: SIGTERM lets the finally
block run and the assertion would be green with this change reverted. It fails
that way, and passes with it, in well under a second.
Six refusals in the runtime called _exit(134) where every other error had
learned to park: no restart by that name, a restart taken with the wrong
arguments or with none, a defer that invoked one, a null allocator, and
free-all on something with no region. Under a merged flan dev the compiler is
in that process, so a program that named a restart nobody established took the
session down with it, which is the one thing the break loop exists to prevent.
They park now. Not through flan_break_hook, which is what bounds and
arithmetic use: that hook may answer by aiming a transfer channel, and these
six are called by emitted code that falls off the end with no channel anywhere
in the call, so a restart chosen against one would be accepted and dropped.
flan_trap_hook says the other thing instead — stop here, let everything be
read, and refuse the resume with a reason.
All six park, for two reasons rather than one. Four are guards that fire
before the operation they guard, so nothing is half done and the frame reads
like any other. The other two fire mid-transfer, with the frame's defers
possibly half run, and they park only to be looked at: stopping on a torn
unwind is strictly more than exiting before anyone can ask what tore it.
The break loop grew a per-snapshot resumable flag for it. Restarts are still
listed and still numbered, the terminal marks them untakeable and the socket
reports the same positions as unreachable, and the listener refuses a choice
with the trap's own sentence rather than the thunk-boundary one.
Standalone builds die exactly as they did: nothing installs the hook in a
program that did not import the agent, and the acceptance case for free-all
still wants exit 134 and the same message.
The review entry that asked for this named flan_exit_hook, which is normal
termination and not this at all; it is struck out with the correction.
Retrying immediately looked like eight chances and was one: a walk that bails
at the epoch check costs almost nothing, so all eight fit inside the single
compaction they were all losing to, and the listing refused having waited for
nothing. A quarter of a millisecond between attempts -- the agent's break-loop
idiom, legal here because the waiter is the listener thread and never the game
loop -- bounds the whole refusal at two milliseconds. Measured with a writer
noting and freeing on top of three thousand live blocks: 8 right answers in 200
without the pause, 200 in 200 with it. It is not magic, and the comment says
so: a writer that spends most of its time rearranging the table still gets
refused, which is the honest answer and used to be a zero-row lie.
The two cases the last commit left unwired are wired now, and a third joins
them: a listing taken while the table really is being compacted, which nothing
covered -- the full-of-live case never compacts and the churn case is
single-threaded, so the retry itself was exercised by nothing. It asserts only
what a slower machine cannot change: never zero rows, never a count that is
neither right nor a refusal. How the rest divides is printed, not pinned.
The three named arms are not every way a step after the check can fail.
write_file makes the daemon's copy of the module's text before llc is called at
all, and a Sys_error from it went out through serve's guard with the session
already holding the declaration — the same stranded declaration under a
different exception. Dev.eval now restores on the way past anything that
escapes, and carries an accepted flag so that a module the agent has already
taken is never rolled back out from under the process.
That is also the seam the crash can be reproduced through. test_dev takes the
daemon's working directory away from it — its own, not the macro cache the two
failures above use, which cannot fail a build with no macro in it — evaluates a
defn, and then calls it. Without the restore the daemon lists probe-two in
describe and the call closes the socket: the null cell, the game thread, and
address 0.
Two seconds was measured on one warm machine and has no margin against the
6.8s cold build listening already records. The status and the absence of the
frame-boundary sentence are what discriminate; this bound exists only so a
timeout cannot be read as an answer, so it moves to 4.5 and says so.
(/ 0.0 0.0) printed nan through LLVM, which folds it at compile time to
the positive quiet NaN, and -nan through x86, where divsd computes the
negative one. Put the operands in globals so nothing folds and both say
-nan, so the divergence is the folding path and not the arithmetic.
The sign bit of a NaN is not a property of the number and IEEE 754 does
not specify it, so the print site is where this is answered.
flan_f64_to_bytes renders any NaN as nan, and the two dev emitters do
the same. That is not a new rule: format-f64 in the prelude has always
answered nan for this value, so a build where (print x) said -nan and
(show x 2) said nan was contradicting itself inside one backend. An
infinity still prints signed.
format.flan prints the three non-finite values through print as well as
through show. It is in the survey corpus, so the one program pins the
printed form under dune test and the agreement between backends under
the survey.
The registry compacted whenever the table was three quarters full, and a
compaction reclaims dead entries and nothing else. A program holding more than
three quarters of the table in live blocks therefore compacted on every
allocation for the rest of its life, reclaiming nothing each time and holding
the table-wide epoch odd while it did. A listing racing that loop lost all
eight of its attempts and answered with zero rows -- "nothing is held", about a
program holding three thousand blocks, from the verb that exists to find a
leak. Measured at 199 wrong answers in 200.
The trigger now also asks whether there is an eighth of a table's worth of dead
to reclaim, which is a count four places maintain: a death, an arena's
free-all, a note written over a dead slot, and the sweep itself. That bounds
the cost from the other side too, since a sweep that runs reclaims at least 512
slots and so cannot run twice in 512 allocations.
Separately, flan_dev_reg_by_type answered a walk it could not take with zero
rows, which is the same number a program that had freed everything gets, and
stepped past slots flan_reg_snap could not copy while still calling the walk
whole. It now counts those slots and returns -1 with the count, the agent
refuses in a sentence the daemon already renders, and the snap contract says
which caller keeps it and why reg_at is allowed not to.
A note that finds no slot is still dropped -- dying because a diagnostic ran out
of room would be the diagnostic shooting the patient -- and now says so on
stderr once, quoting how many entries were dead rather than claiming the table
is all live.
test/dev_limits.c gains three modes, driven from test_reload: 3100 live blocks
read under a writer thread (1 right in 200 before, 200 after), 3000 live with
600 churned on top of them to prove the sweep still runs, and a genuinely full
table that must say so exactly once.
The lo <= hi test in check_slice and slice-from-ptr's n >= 0 sat behind
--no-bounds-checks in both backends, while the comment beside each said
they could not be dropped. They are not bounds checks: hi <= len asks
whether a range fits inside a length, and lo <= hi asks whether the word
about to be written into a %slice's length field is a count at all. The
first stays behind the flag, the second is now emitted everywhere, the
way flan_vec_as_slice has always validated its own l > h in plain C.
emit.ml emits two signal blocks rather than one and i1, so an unchecked
build carries one compare. x86.ml keeps all three frame temporaries
stored outside the flag and gates only the second compare, because the
third is the length the message prints.
The IR assertion in test_acceptance now says the two slice calls are
present under --no-bounds-checks rather than absent, and the same build
is run: case 2 and case -2 of bounds.flan must still die.
The merged build's stdout is a 64K pipe back into the daemon's own process,
and the accept loop is the only thing reading it -- which it is not doing
while serve is answering a request. The two five-second waits for a frame
boundary now drain the pipe on every tick, so a program stopped inside fwrite
is one the daemon lets go rather than one it waits out and then accuses of
not calling agent/poll.
drain and not take: the text stays in the buffer until with_output puts it on
the reply, which is where the output an evaluation caused belongs. And the
drain sits beside the sleep rather than inside the select, because a readable
pipe would make the tick free and count the timeout out in a fraction of it.
dev-chatty.flan prints 4K a frame, which is the only fixture here that fills
the pipe at all; without the drain it fails in 5.1s with the old sentence.
The members of a defenum are i32 at run time, but the reader hands the parser
an int64, so a value too large for the type arrived looking ordinary: truncated
by the x86 backend, malformed in the LLVM IR, and -- the reason this is a
correctness hole and not a nicety -- invisible to the duplicate-value rule
sitting right below it. That rule compares int64s, so (defenum E [A 0
B 4294967296]) passed it: the two differ as int64 and are both 0 as i32, and
the one check written to catch two names for one number waved through exactly
the case it exists for.
Each value is now checked where it is resolved, which is before the collision
scan runs, so the scan compares the numbers the program will actually have. A
value that does not fit is refused rather than quietly made to fit, naming the
member, its enum, and the value, with a different sentence for a value that was
written and one autoincrement walked into -- nothing in the source wrote
2147483648, so the refusal has to say where it came from before it can say it
is wrong.
The check is bound with a let rather than inlined into the cons, and that is
load-bearing: OCaml leaves :: operand order unspecified and takes the tail
first, so an inlined check would run after the recursive Int64.add and let
(defenum E [A 9223372036854775807 B]) wrap to min_int and refuse B for a number
in no one's source. Bound first, A is refused and the wrap is unreachable.
The parser is the only place this needs to happen: Parse.decl is the sole
constructor of Ast.Defenum's member values, and Load only re-qualifies the
enum's name.
Explicit-duplicate aliasing is untouched; that rule is deliberate.
The condition was checked before in_loop, outside the diff that catches a
loop giving away what the next iteration needs. Emit puts the condition in
the loop header, so it runs again every trip: a condition that frees a
local freed it once per trip. It is now diffed against the same dead set,
with its own reason. A dotimes count and a loop's initial values stay
outside: those are evaluated exactly once.
The agent refuses a module it has no room to queue with "the program is not
calling agent/poll". For a running program that is the cause. For a parked one
it is confidently wrong: there is no game thread left to poll with, nothing
drains the ring until somebody runs the program again, and the ring is full
precisely because Dev.eval accepts evaluations while parked and promises they
install at the next run. At install sixty-five that promise breaks, and the
reply sent the reader to inspect a loop that is not running.
The agent cannot know this — parking is the merged shim's state — so the
daemon, which has just asked liveness, rewrites that one reply the way
abi_mismatch rewrites dlerror's. Every other refusal is still quoted in the
agent's own words, and a running program's is unchanged.
Pinned on Dev.refusal rather than end to end: filling the ring is sixty-four
real clang runs, and what the daemon does with the agent's words is the whole
of the change.
